A process for preparing a precision casting mold shell of titanium alloy

Abstract

The application provides a preparation process of a titanium alloy precision casting shell, and comprises the following steps: S1, preparing a wax mold; S2, weighing yttrium oxide and zirconium oxide, mixing them uniformly, electrically melting, crushing, vibrating, and screening to obtain yttrium powder, then adding calcium fluoride and carbon fibers to mix uniformly to obtain a surface layer powder; S3, adding the surface layer powder into zirconium acetate and adding a defoaming agent, stirring to obtain a surface layer coating; S4, uniformly dipping the wax mold module in the surface layer coating, then controlling the slurry, spraying sand, and drying; S5, reinforcing layer shell preparation: preparing a reinforcing layer slurry by using silica sol and mullite powder, and adjusting the viscosity value to a proper value; the reinforcing layer sand is 30-60 mesh mullite sand, and the wax mold module is repeatedly coated with the reinforcing layer for 5-7 layers, wherein the half layer is only dipped in the slurry without spraying sand; S6, dewaxing; and S7, baking. The application can simplify the preparation process, facilitate the operation and the consistency control of the quality, and realize steam dewaxing, so that the problem of environmental pollution caused by zirconium acetate chemical dewaxing is solved.

Description

Technical Field

[0001] This invention relates to the field of titanium alloy shell manufacturing technology, and particularly to a manufacturing process for a precision casting titanium alloy shell. Background Technology

[0002] Titanium alloys, due to their low density, high specific strength, corrosion resistance, and non-magnetic properties, are important materials for structural components in high-end equipment manufacturing. The physicochemical and metallurgical properties of titanium dictate the unique characteristics of titanium alloy structural component forming methods and molding materials. Currently, the main casting method for titanium alloys is investment casting using oxide ceramic shells. The ceramic powders mainly include yttrium oxide and zirconium oxide, and the surface binders mainly include zirconium acetate, yttrium sol, and zirconium carbonate ammonium. Yttrium oxide and zirconium acetate are suitable surface materials for titanium alloys. However, because zirconium acetate has the characteristic of dissolving in water, various units in the titanium alloy industry perform various modification treatments on the surface zirconium acetate, making the surface shell preparation process cumbersome and increasing the instability of the production process and quality.

[0003] In the preparation method of the oxide-ceramic composite shell for precision casting of titanium alloy (CN104001856A), the method for preparing the surface binder involves adding diluted wetting agent and defoamer to a zirconium sol solution while stirring during the addition process. Finally, ammonia water is added to the solution and stirred to complete the preparation of the surface binder. Zirconia powder is then added to the prepared surface binder and stirred to form a surface coating. This method suffers from a cumbersome preparation process.

[0004] Therefore, there is an urgent need to develop a molding and shell preparation process for precision casting of titanium alloys to simplify operations and formulas, and improve the stability of production operations and quality. Summary of the Invention

[0005] In view of this, the present invention aims to propose a manufacturing process for precision casting shells of titanium alloys, so as to solve the problems of cumbersome shell preparation and material re-dissolution upon contact with water during the dewaxing process in the prior art.

[0006] To achieve the above objectives, the technical solution of the present invention is as follows: a process for preparing a precision-cast titanium alloy shell, comprising the following steps:

[0007] S1. Prepare wax models;

[0008] S2. Preparation of surface layer powder: Weigh yttrium oxide and zirconium oxide separately, mix them evenly and electro-melt them, then crush, vibrate and sieve to obtain yttrium powder, then add calcium fluoride and carbon fiber and mix evenly to obtain surface layer powder;

[0009] S3. Preparation of topcoat: Add the topcoat powder to the topcoat binder and add the defoamer, stir for 30-60 minutes to obtain the topcoat; the topcoat binder is zirconium acetate;

[0010] S4. Surface shell making: After the wax model is evenly immersed in the surface coating, the slurry is controlled. When the surface slurry no longer flows, sand is poured on. After evenly pouring sand, it is dried for 8-12 hours.

[0011] S5. Reinforcing layer shell preparation: Prepare reinforcing layer slurry with silica sol and mullite powder, and adjust to a suitable viscosity value; the reinforcing layer sand is 30-60 mesh mullite sand. The wax mold module obtained in step S4 is repeated with 5-7 and a half layers of reinforcing layer, of which half layer is only impregnated with slurry and not coated with sand.

[0012] S6. Dewaxing: The module obtained in step S5 is subjected to steam dewaxing at a pressure of 0.4-0.6 MPa and a time of 3-6 seconds.

[0013] S7. Firing: Firing the dewaxed shell obtained in step S6 to obtain a shell for casting.

[0014] Furthermore, in step S2, the yttrium oxide content is 95-97%, and the zirconium oxide content is 3-5%.

[0015] Furthermore, in step S2, the yttrium powder with a mesh size ≤ 200 accounts for 60-65%, the yttrium powder with a mesh size of 200 < 1500 accounts for 20-25%, and the yttrium powder with a mesh size of 1500 < 5000 accounts for 15%.

[0016] Furthermore, in step S2, the amount of calcium fluoride added is 0.1-0.5%, and the mesh size is 1500 mesh.

[0017] Furthermore, in step S2, the amount of carbon fiber added is 0.1-0.3%, the diameter is 7μm-8μm, and the length is 1-3mm.

[0018] Furthermore, in step S3, the content of zirconium acetate is 25-35%, of which the content of free acetic acid is 8-15%.

[0019] Furthermore, in step S3, the zirconium acetate has a particle size of 2-4 nm and a potential of 15-20 mV.

[0020] Furthermore, in step S3, the powder-to-liquid ratio of the surface layer powder and the surface layer adhesive is 4.5:1-5:1.

[0021] Furthermore, in step S3, the defoamer is selected from any one of n-octanol, n-pentanol, and isopropanol.

[0022] Furthermore, in step S4, zirconium oxide sand is used as the surface sand for rinsing during the surface shell preparation process, with a mesh size of 60-120.

[0023] Furthermore, in step S5, the viscosity values ​​of reinforcing layer 1 to reinforcing layer 4 are 10-15s, and the viscosity values ​​of reinforcing layer 5 to reinforcing layer 7 are 30-45s.

[0024] Compared with existing technologies, the manufacturing process of a precision casting shell for titanium alloy described in this invention has the following advantages:

[0025] (1) Using only zirconium acetate as the surface binder and adjusting the physical properties of zirconium acetate such as particle size and potential, using yttrium oxide and zirconium oxide as surface powder and adjusting their ratio and particle size, can simplify the preparation process and facilitate the consistent control of operation quality.

[0026] (2) Adding carbon fiber to the surface powder can prevent slag shedding and improve the quality of the prepared shell.

[0027] (3) It can achieve steam dewaxing and solve the environmental pollution problem caused by zirconium acetate chemical dewaxing;

[0028] (4) The prepared surface shell has a small interface reaction and a contamination thickness of <2μm, which can be removed by sandblasting, simplifying the operation process. Attached Figure Description

[0029] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings:

[0030] Figure 1 The contamination layer of the titanium casting prepared in Example 1 of this invention;

[0031] Figure 2 The contamination layer of the titanium casting prepared in Example 2 of this invention;

[0032] Figure 3 The contamination layer of the titanium casting prepared in Example 3 of this invention;

[0033] Figure 4 The contamination layer on the titanium casting prepared in Comparative Example 1;

[0034] Figure 5 The contamination layer on the titanium casting prepared in Comparative Example 2;

[0035] Figure 6 The titanium casting prepared for Comparative Example 3;

[0036] Figure 7 The titanium casting prepared for Comparative Example 4. Detailed Implementation

[0037] The present invention will be further described below with reference to specific embodiments. First, it should be noted that the data in the following experimental examples were obtained by the inventors through numerous experiments. Due to space limitations, only a portion of these data is shown in the specification, and those skilled in the art can understand and implement the present invention based on this data. These embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Furthermore, it should be understood that after reading the contents of this invention, those skilled in the art can make various modifications or alterations to the invention, and these modifications or alterations also fall within the scope of protection of this application.

[0038] The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0039] Example 1: Preparation of a thin-walled ZTC4 titanium alloy precision casting mold shell

[0040] S1. Prepare wax models;

[0041] S2. Weigh yttrium oxide and zirconium oxide at a mass ratio of 95:5, mix them evenly, and electro-melt them. After crushing, vibrating, and sieving, yttrium powder is obtained, with 60% of the yttrium powder having a mesh size ≤200, 25% having a mesh size between 200 and 1500, and 15% having a mesh size between 1500 and 5000. Then, calcium fluoride and carbon fiber are added and mixed evenly to obtain the surface powder. The amount of calcium fluoride added is 0.12% with a mesh size of 1500, and the amount of carbon fiber added is 0.1%, with a diameter of 7μm-8μm and a length of 1-3mm.

[0042] S3. Add the topcoat powder to the topcoat binder zirconium acetate at a powder-to-liquid ratio of 4.5:1, and add the defoamer n-octanol. Stir for 30 minutes to obtain a topcoat coating with a suitable viscosity. The zirconium acetate has a particle size of 2.05 nm, a zirconium acetate content of 25%, a free acetic acid content of 8%, and a zirconium acetate potential of 15 mV.

[0043] S4. After uniformly immersing the wax model assembly in the surface coating, control the slurry. When the surface coating no longer flows, sprinkle 60-120 mesh zirconia sand evenly and dry for 8 hours.

[0044] S5. Mix silica sol and mullite powder to prepare the reinforcement layer slurry and adjust it to a suitable viscosity value. The reinforcement layer sand is 30-60 mesh mullite sand. Repeat the reinforcement layer 5 and a half times, in which half layer is only impregnated with slurry and not sand. The viscosity value of reinforcement layer 1 to reinforcement layer 4 is 11s, and the viscosity value of reinforcement layer 5 is 32s.

[0045] S6. Place the module obtained in step 5 into the dewaxing kettle for steam dewaxing. The dewaxing pressure is 0.4 MPa and the dewaxing time is 4 s.

[0046] S7. The shell obtained in step S6 is baked to obtain a shell for casting.

[0047] like Figure 1 The image shows the contamination layer of the ZTC4 titanium casting prepared in Example 1, with a thickness of 0.

[0048] Example 2: Preparation of a thin-walled ZTA15 titanium alloy precision casting mold shell

[0049] S1. Prepare wax models;

[0050] S2. Weigh yttrium oxide and zirconium oxide at a mass ratio of 96:4, mix them evenly, and electro-melt them. After crushing, vibrating, and sieving, yttrium powder is obtained, with 63% of the yttrium powder having a mesh size ≤200, 22% having a mesh size between 200 and 1500, and 15% having a mesh size between 1500 and 5000. Then, calcium fluoride and carbon fiber are added and mixed evenly to obtain the surface powder. The amount of calcium fluoride added is 0.3% with a mesh size of 1500, and the amount of carbon fiber added is 0.2% with a diameter of 7μm-8μm and a length of 1-3mm.

[0051] S3. Add the topcoat powder to the topcoat binder zirconium acetate at a powder-to-liquid ratio of 4.8:1, and add the defoamer n-octanol. Stir for 30 minutes to obtain a topcoat coating with a suitable viscosity. The zirconium acetate has a particle size of 3.08 nm, a zirconium acetate content of 30%, a free acetic acid content of 12%, and a zirconium acetate potential of 18 mV.

[0052] S4. After uniformly immersing the wax model assembly in the surface coating, control the slurry. When the surface slurry no longer flows, sprinkle 60-120 mesh zirconia sand evenly and dry for 10 hours.

[0053] S5. Mix silica sol and mullite powder to prepare the reinforcement layer slurry and adjust it to a suitable viscosity value. The reinforcement layer sand is 30-60 mesh mullite sand. Repeat the reinforcement layer 7 and a half times, in which half layers are only impregnated with slurry and not sand. The viscosity value of reinforcement layer 1 to reinforcement layer 4 is 13s, and the viscosity value of reinforcement layer 5 to reinforcement layer 7 and a half times is 40s.

[0054] S6. Place the module obtained in step 5 into a dewaxing kettle for steam dewaxing. The dewaxing pressure is 0.5 MPa and the dewaxing time is 4.5 s.

[0055] S7. The shell obtained in step S6 is baked to obtain a shell for casting.

[0056] like Figure 2 The image shows the contamination layer of the ZTA15 titanium casting prepared in Example 2, with a thickness of 0.

[0057] Example 3: Preparation of a thin-walled Ti811 titanium alloy precision casting mold shell

[0058] S1. Prepare wax models;

[0059] S2. Weigh yttrium oxide and zirconium oxide at a mass ratio of 97:3, mix them evenly, and electro-melt them. After crushing, vibrating, and sieving, yttrium powder is obtained, with 65% of the yttrium powder having a mesh size ≤200, 20% having a mesh size between 200 and 1500, and 15% having a mesh size between 1500 and 5000. Then, calcium fluoride and carbon fiber are added and mixed evenly to obtain the surface powder. The amount of calcium fluoride added is 0.5% with a mesh size of 1500, and the amount of carbon fiber added is 0.3% with a diameter of 7μm-8μm and a length of 1-3mm.

[0060] S3. Add the topcoat powder to the topcoat binder zirconium acetate at a powder-to-liquid ratio of 4.5:1, and add the defoamer n-octanol. Stir for 30 minutes to obtain a topcoat with a suitable viscosity. The zirconium acetate has a particle size of 3.98 nm, a zirconium acetate content of 35%, a free acetic acid content of 15%, and a zirconium acetate potential of 20 mV.

[0061] S4. After uniformly immersing the wax model assembly in the surface coating, control the slurry. When the surface slurry no longer flows, sprinkle 60-120 mesh zirconia sand evenly and dry for 12 hours.

[0062] S5. Mix silica sol and mullite powder to prepare the reinforcement layer slurry and adjust it to a suitable viscosity value. The reinforcement layer sand is 30-60 mesh mullite sand. Repeat the reinforcement layer 7 and a half times, in which half layers are only impregnated with slurry and not sand. The viscosity value of reinforcement layer 1 to reinforcement layer 4 is 15s, and the viscosity value of reinforcement layer 5 to reinforcement layer 7 and a half times is 45s.

[0063] S6. Place the module obtained in step 5 into the dewaxing kettle for steam dewaxing. The dewaxing pressure is 0.6 MPa and the dewaxing time is 3 seconds.

[0064] S7. The shell obtained in step S6 is baked to obtain a shell for casting.

[0065] like Figure 3 The image shows the contamination layer of the Ti811 titanium casting prepared in Example 3, with a thickness of 0.

[0066] Comparative Example 1

[0067] S1. Prepare wax models;

[0068] S2. Weigh yttrium oxide and zirconium oxide at a mass ratio of 95:5, mix them evenly, and electro-melt them. After crushing, vibrating, and sieving, yttrium powder is obtained, with 60% of the yttrium powder having a mesh size ≤200, 25% having a mesh size between 200 and 1500, and 15% having a mesh size between 1500 and 5000. Then, calcium fluoride and carbon fiber are added and mixed evenly to obtain the surface powder. The amount of calcium fluoride added is 0.12% with a mesh size of 1500, and the amount of carbon fiber added is 0.1%, with a diameter of 7μm-8μm and a length of 1-3mm.

[0069] S3. Add the topcoat powder to the topcoat binder zirconium acetate at a powder-to-liquid ratio of 4.5:1, and add the defoamer n-octanol. Stir for 30 minutes to obtain a topcoat with a suitable viscosity. The zirconium acetate has a particle size of 5-7 nm, a zirconium acetate content of 25%, a free acetic acid content of 8%, and a zirconium acetate potential of 15 mV.

[0070] S4. After uniformly immersing the wax model assembly in the surface coating, control the slurry. When the surface coating no longer flows, sprinkle 60-120 mesh zirconia sand evenly and dry for 8 hours.

[0071] S5. Mix silica sol and mullite powder to prepare the reinforcement layer slurry and adjust it to a suitable viscosity value. The reinforcement layer sand is 30-60 mesh mullite sand. Repeat the reinforcement layer 5 and a half times, in which half layer is only impregnated with slurry and not sand. The viscosity value of reinforcement layer 1 to reinforcement layer 4 is 11s, and the viscosity value of reinforcement layer 5 is 32s.

[0072] S6. Place the module obtained in step 5 into the dewaxing kettle for steam dewaxing. The dewaxing pressure is 0.4 MPa and the dewaxing time is 4 s.

[0073] S7. The shell obtained in step S6 is calcined to obtain a ZTC4 titanium alloy shell for casting.

[0074] like Figure 4 As shown, the thickness of the contamination layer on the surface of the casting prepared in Comparative Example 1 was 71 μm. Comparative Example 1 achieved a larger contamination layer thickness by changing the particle size of zirconium acetate.

[0075] Comparative Example 2

[0076] S1. Prepare wax models;

[0077] S2. Weigh yttrium oxide and zirconium oxide at a mass ratio of 96:4, mix them evenly, and electro-melt them. After crushing, vibrating, and sieving, yttrium powder is obtained, with 63% of the yttrium powder having a mesh size ≤200, 22% having a mesh size between 200 and 1500, and 15% having a mesh size between 1500 and 5000. Then, calcium fluoride and carbon fiber are added and mixed evenly to obtain the surface powder. The amount of calcium fluoride added is 0.3% with a mesh size of 1500, and the amount of carbon fiber added is 0.2% with a diameter of 7μm-8μm and a length of 1-3mm.

[0078] S3. Add the topcoat powder to the topcoat binder zirconium acetate at a powder-to-liquid ratio of 4.8:1, and add the defoamer n-octanol. Stir for 30 minutes to obtain a topcoat coating with a suitable viscosity. The zirconium acetate has a particle size of 3.08 nm, a zirconium acetate content of 30%, a free acetic acid content of 12%, and a zirconium acetate potential of 14 mV.

[0079] S4. After uniformly immersing the wax model assembly in the surface coating, control the slurry. When the surface slurry no longer flows, sprinkle 60-120 mesh zirconia sand evenly and dry for 10 hours.

[0080] S5. Mix silica sol and mullite powder to prepare the reinforcement layer slurry and adjust it to a suitable viscosity value. The reinforcement layer sand is 30-60 mesh mullite sand. Repeat the reinforcement layer 7 and a half times, in which half layers are only impregnated with slurry and not sand. The viscosity value of reinforcement layer 1 to reinforcement layer 4 is 13s, and the viscosity value of reinforcement layer 5 to reinforcement layer 7 and a half times is 40s.

[0081] S6. Place the module obtained in step 5 into a dewaxing kettle for steam dewaxing. The dewaxing pressure is 0.5 MPa and the dewaxing time is 4.5 s.

[0082] S7. The shell obtained in step S6 is calcined to obtain a ZTA15 titanium alloy shell for casting.

[0083] like Figure 5 As shown, the thickness of the contamination layer on the surface of the casting prepared in Comparative Example 2 was 62 μm. Comparative Example 2 achieved a larger contamination layer thickness on the casting due to the change in the potential of zirconium acetate.

[0084] Comparative Example 3

[0085] S1. Prepare wax models;

[0086] S2. Weigh yttrium oxide and zirconium oxide at a mass ratio of 99:1, mix them evenly, and electro-melt them. After crushing, vibrating, and sieving, yttrium powder is obtained, with 65% of the yttrium powder having a mesh size ≤200, 20% having a mesh size between 200 and 1500, and 15% having a mesh size between 1500 and 5000. Then, calcium fluoride and carbon fiber are added and mixed evenly to obtain the surface powder. The amount of calcium fluoride added is 0.5% with a mesh size of 1500, and the amount of carbon fiber added is 0.3% with a diameter of 7μm-8μm and a length of 1-3mm.

[0087] S3. Add the topcoat powder to the topcoat binder zirconium acetate at a powder-to-liquid ratio of 4.5:1, and add the defoamer n-octanol. Stir for 30 minutes to obtain a topcoat with a suitable viscosity. The zirconium acetate has a particle size of 3.98 nm, a zirconium acetate content of 35%, a free acetic acid content of 15%, and a zirconium acetate potential of 20 mV.

[0088] S4. After uniformly immersing the wax model assembly in the surface coating, control the slurry. When the surface slurry no longer flows, sprinkle 60-120 mesh zirconia sand evenly and dry for 12 hours.

[0089] S5. Mix silica sol and mullite powder to prepare the reinforcement layer slurry and adjust it to a suitable viscosity value. The reinforcement layer sand is 30-60 mesh mullite sand. Repeat the reinforcement layer 7 and a half times, in which half layers are only impregnated with slurry and not sand. The viscosity value of reinforcement layer 1 to reinforcement layer 4 is 15s, and the viscosity value of reinforcement layer 5 to reinforcement layer 7 and a half times is 45s.

[0090] S6. Place the module obtained in step 5 into the dewaxing kettle for steam dewaxing. The dewaxing pressure is 0.6 MPa and the dewaxing time is 3 seconds.

[0091] S7. The shell obtained in step S6 is calcined to obtain a Ti811 titanium alloy shell for casting.

[0092] like Figure 6 The casting shown is prepared in Comparative Example 3. Due to the unsuitable ratio of yttrium oxide and zirconium oxide, the surface slurry has poor coating properties. After the surface slurry is impregnated and sand is applied, it accumulates and cannot continue to be cast.

[0093] Comparative Example 4

[0094] S1. Prepare wax models;

[0095] S2. Weigh yttrium oxide and zirconium oxide at a mass ratio of 95:5, mix them evenly, and electro-melt them. After crushing, vibrating, and sieving, yttrium powder is obtained, with 60% of the yttrium powder having a mesh size ≤200, 25% having a mesh size between 200 and 1500, and 15% having a mesh size between 1500 and 5000. Then, calcium fluoride is added and mixed evenly to obtain the surface powder. The amount of calcium fluoride added is 0.12%, and the mesh size is 1500.

[0096] S3. Add the topcoat powder to the topcoat binder zirconium acetate at a powder-to-liquid ratio of 4.5:1, and add the defoamer n-octanol. Stir for 30 minutes to obtain a topcoat coating with a suitable viscosity. The zirconium acetate has a particle size of 2.05 nm, a zirconium acetate content of 25%, a free acetic acid content of 8%, and a zirconium acetate potential of 15 mV.

[0097] S4. After uniformly immersing the wax model assembly in the surface coating, control the slurry. When the surface coating no longer flows, sprinkle 60-120 mesh zirconia sand evenly and dry for 8 hours.

[0098] S5. Mix silica sol and mullite powder to prepare the reinforcement layer slurry and adjust it to a suitable viscosity value. The reinforcement layer sand is 30-60 mesh mullite sand. Repeat the reinforcement layer 5 and a half times, in which half layer is only impregnated with slurry and not sand. The viscosity value of reinforcement layer 1 to reinforcement layer 4 is 11s, and the viscosity value of reinforcement layer 5 is 32s.

[0099] S6. Place the module obtained in step 5 into the dewaxing kettle for steam dewaxing. The dewaxing pressure is 0.4 MPa and the dewaxing time is 4 s.

[0100] S7. The shell obtained in step S6 is baked to obtain a shell for casting.

[0101] like Figure 7 As shown, Comparative Example 4 does not contain carbon fiber. The prepared surface layer is dewaxed by steam without re-dissolving. The surface layer of the shell has low strength, and the casting has internal slag defects during flaw detection.

[0102] The manufacturing process of the precision casting shell for titanium alloy described in this invention improves upon the traditional methods used in the titanium alloy industry for adding various modifiers or composite surface layer adhesives to the surface layer binder. This simplifies the surface layer preparation process, making the formulation of the surface layer coating easier for on-site operators and ensuring consistent and stable operational quality. Furthermore, the surface layer shell prepared using zirconium acetate and yttrium oxide powder can be dewaxed using steam, causing no environmental pollution. The interfacial reaction between the surface layer and molten titanium is minimal, resulting in a contamination layer thickness of less than 2 μm, which can be removed by sandblasting, thus guaranteeing the appearance quality of the titanium alloy casting.

[0103] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A manufacturing process for a precision-cast titanium alloy shell, characterized in that, Includes the following steps: S1. Prepare wax models; S2. Preparation of surface layer powder: Weigh yttrium oxide and zirconium oxide separately, mix them evenly and electro-melt them, then crush, vibrate and sieve to obtain yttrium powder. The yttrium powder contains 95-97% yttrium oxide and 3-5% zirconium oxide. 60-65% of the yttrium powder has a mesh size ≤200, 20-25% has a mesh size <1500 and a mesh size <1500 and a mesh size <5000 and a mesh size <15%. Then add calcium fluoride and carbon fiber and mix evenly to obtain the surface layer powder. S3. Preparation of topcoat: Add the topcoat powder to the topcoat binder and add defoamer, stir for 30-60 minutes to obtain the topcoat; the topcoat binder is zirconium acetate, the particle size of zirconium acetate is 2-4 nm, and the potential is 15-20 mV; S4. Surface shell making: After the wax model is evenly immersed in the surface coating, the slurry is controlled. When the surface slurry no longer flows, sand is poured on. After evenly pouring sand, it is dried for 8-12 hours. S5. Reinforcing layer shell preparation: Prepare reinforcing layer slurry with silica sol and mullite powder, and adjust to a suitable viscosity value; the reinforcing layer sand is 30-60 mesh mullite sand. The wax mold module obtained in step S4 is repeated with 5-7 and a half layers of reinforcing layer, of which half layer is only impregnated with slurry and not coated with sand. S6. Dewaxing: The module obtained in step S5 is subjected to steam dewaxing at a pressure of 0.4-0.6 MPa and a time of 3-6 seconds. S7. Firing: Firing the dewaxed shell obtained in step S6 to obtain a shell for casting.

2. The manufacturing process of the titanium alloy precision casting mold shell according to claim 1, characterized in that, In step S4, zirconium oxide sand is used as the surface sand for rinsing during the surface shell preparation process, with a mesh size of 60-120.

3. The manufacturing process of the titanium alloy precision casting shell according to claim 1, characterized in that, In step S5, the viscosity values ​​of reinforcement layers 1 to 4 are 10-15s, and the viscosity values ​​of reinforcement layers 5 to 7 are 30-45s.

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